Requirements parser works very similarly to the way pip actually parses requirement files except that pip typically proceeds to install the relevant packages.

Requirements come in a variety of forms such as requirement specifiers (such as requirements>=0.0.5), version control URIs, other URIs and local file paths.

Parsing requirement specifiers

import requirements
req = "django>=1.5,<1.6"
parsed = list(requirements.parse(req))[0]       # django
parsed.specs      # [('>=', '1.5'), ('<', '1.6')]
parsed.specifier  # True

Parsing version control requirements

req = "-e git+git://"
parsed = list(requirements.parse(req))[0]      # django_haystack
parsed.vcs       # git
parsed.revision  # 259274e4127f723d76b893c87a82777f9490b960
parsed.uri       # git+git://
parsed.editable  # True (because of the -e option)

Parsing local files

req = "-e path/to/project"
parsed = list(requirements.parse(req))[0]
parsed.local_file    # True
parsed.path          # path/to/project